The invention generally relates to an automatic tea brewer. More specifically, the invention is directed toward brewing tea by means of a siphon-type brewing device which brews a portion of the tea into an extract for mixing with a larger portion of diluting water to make ice tea.
Known brewing devices, such as those used for brewing coffee, have utilized the principle of displacing a volume of hot water from a tank with a volume of cold water introduced generally near the bottom thereof whereby to cause the hot water to be siphoned to a brew basket or brew chamber containing coffee grounds. A few prior art tea brewers have utilized siphon-type brewing functions, but they have employed an inefficient arrangement having separate expansion tanks or separate inlet cold water basins. Certain of these prior art devices have employed a plurality of sensors and time relays to control the volume of water in cooperation with water level floats or probes. Such systems have thereby incorporated unnecessarily complex electrical control systems that often times become maladjusted and can experience clogging of water probes and floats.
It has been a problem in brewing tea to ensure that the brew water that is introduced into the ground tea leaves is at a desirable brewing temperature, usually about 200.degree..+-.5.degree. F. In this regard, when using a siphon-type system, it is important to limit, if not prevent, the mixing of the inletted cold dilute water with the hot water in the tank to maintain the wanted brew temperature. Usually, a loop-type heating element resides within the hot water container for maintaining the water at the prescribed brewing temperature. Thus, if unwanted mixing occurs with cold dilute water, the goal of maintaining the temperature in between brewing cycles is defeated.
While industry standards for brewing tea vary and no one set of guidelines is generally recognized as the preeminent brewing procedure, it has been determined from tea manufacturers, and others in the food services art, particularly those involved with brewing tea in large volumes for restaurant use, that an extract of tea is preferably mixed into the dilute in a proportion of one part of extract to three parts of dilute cold water.
It has been further determined that the mixing of the extract with the dilute is preferable to the reverse in order to prevent a clouding effect that may otherwise occur. With this in mind, it is therefore important that when employing a siphon-type system a controlled volume of dilute is separately introduced to a reservoir to subsequently then receive the proportionate measure of extract in another determined proportion. It has been found that a controlled valve and inlet timing means should be provided whereby the proportions of extract to dilute are unfailingly provided for each batch.
For long and efficient use, it has been discovered from studying prior art deficiencies, that it would be desirable to limit the electronic controls for a siphon-type tea brewing system whereby to preferably inlet a volume of water at a timed solenoid valve comprising the only electrical inlet water volume control in the system.
In addition to achieving the blending of about one-quarter extract to three-quarters dilute, it has also been learned from the food and restaurant industry that providing for a nine to ten minute flow-through steeping period for the tea leaves would be desirable, whereby as a result the one-quarter extract portion is introduced into the dilute during this nine to ten minute period to achieve desired taste and properly extract a tasteful flavor and strength from the tea leaves.
In attempting to minimize the number of major components in a tea brewing system, it has been learned that the provision of the expansion portion for displaced hot water is desirably achieved by providing an additional volume within the hot water container rather than using a separate receptacle or chamber for that purpose. However, in seeking to eliminate these other components and employ the hot water container itself for this function, it has been determined to be important to siphon the hot brew water from the side, to the top, of the container slightly above the normal at-rest level of the hot water, thereby to siphon the water when the volume of hot water is raised to a second higher level caused by the inletting of the cold water at the bottom of the hot water container.
In achieving the prescribed proportion of extract to dilute, it is important that substantially the full siphon amount reach the brew chamber. Therefore, the water tank has been found most efficiently operative when provided with a vent in order to maintain a positive pressure at the opening to the siphon from the tank to vent the tank to the atmosphere in order to prevent suction and allow the system to fully drain the siphon tube. Additionally, the vent affords a safety feature so that in the event that there is an overfill into the hot water tank due to a pressure surge, or a blockage in the siphon, the tank overfill amount may be safely drained through the vent tube that leads, for example, to the brew chamber.
During the end of a brew cycle, it has been found beneficial to ensure that the cold water that is introduced via a fill tube to the bottom of the hot water tank is not siphoned back through the inlet line into the valve at the end of the cold water inlet cycle and thereafter conveyed into the dilute reservoir. Thus, it has been found necessary to in some way vent the tank inlet line to atmosphere in order to prevent a reverse siphoning of the water from the bottom of the hot water tank.
Further, in venting the cold inlet water line it has also been discovered that it is important to make sure that the cold dilute water is prevented from being siphoned to the hot water tank or to the brew chamber. Therefore, a desirable system would provide for negative pressure being created generally along the vent of the cold water inlet line whereby to make sure that the vent line for the cold water line is prevented from conducting flow toward the hot water tank or to the brew chamber.
The foregoing problems and impediments found in providing a siphon-system for brewing tea have been overcome by my unique tea brewer. The inventive tea brewer may be summarized as comprising a simplified siphon-system requiring only four major component consisting of: a heated tank for maintaining the brew water at the appropriate temperature; a needle valve assembly for proportionately directing inletted cold water in part to the hot water tank for brewing and in larger part to a dilute reservoir for later mixing with the brewed extract; a water flow timer for inletting the appropriate amount of flow to the valve; and, a solenoid valve associated with the water flow timer to be opened and closed in time controlled sequences. The needle valve assembly is adjustable for maintaining different extractions as might be required with changed water conditions or qualities of tea. The needle valve assembly is positively pressurized throughout the brewing cycle to run full. Positive pressure is achieved by a restrictor along the dilute outlet side of the needle valve whereby the brew water proportion directed through another outlet side is not starved so that is positively pressured throughout the timed period for inletting the cold tap water that is received from the solenoid controlled inlet valve.
The hot water tank is cooperative with a siphon tube, or brew water take or line having an expansion accommodating drip-resistant outlet elbow that receives hot water from the hot water tank beginning when it reaches a certain level as it is pushed upwardly by the inletted cold water at the bottom of the tank. A vent as provided through a generally sealed cover of the tank which vents to atmosphere generally above at a spray disc over the brew chamber. Thereby the siphon or brew water line is kept under positive pressure throughout the cycle so that all the brew water is siphoned to the brew chamber by preventing negative pressure in the water tank above the inlet to the siphon tube.
At the end of the timed solenoid valve cycle for inletting cold water, a reverse siphoning of water from the cold water inlet of the hot water tank is prevented by venting the system to ensure that a positive pressure is maintained in the cold water inlet line. The venting is achieved by a vent tube at the cover of the hot water tank being joined to a branch of a Y-connector arranged along the dilute inlet line downstream of the restrictor and needle valve whereby to ensure that cold water is not siphoned back into the needle valve but is instead directed into the bottom of the hot water tank. The venting is most critical near the end of the timed inlet cycle. This assures that the intended amount of brew water is properly delivered to the hot water tank. Further, in order to prevent the unintended siphoning of cold water from the dilute water line into this first mentioned vent line, the restricted high pressure flow caused by the restrictor is created upstream and through the straight line portion of the Y-connector which creates a negative pressure at the angled branch of the Y-connector that connects to the vent tube. The negative pressure draws the vent line clear so that it sucks water toward the dilute and stops the cold dilute water from reaching the spray head and disc assembly via the vent line.
The tea leaves are placed into the brew chamber arranged under a spray head and perforated disk at the outlet end of siphon tube and are bathed in the siphoned water from the hot water tank. An appropriately sized outlet orifice is provided at a sump in the bottom of the brew chamber for delivery into the reservoir holding the separately inletted dilute portion of the water. The siphon system, brew chamber, and oulet orifice, are provided to have a flow-through steep time of about nine to ten minutes as generally preferred and suggested by the manufacturers of tea blends.
The reservoir is independently movable and may be taken to a remote service location when a brew cycle is done. The reservoir preferably includes a spigot valve and an associating sight gauge for determining the level of tea therein, whereby the tea may be dispensed into a glass filled with ice for service to the custom. After one brew has been completed, another reservoir of like design may be placed in association with the siphon system, and a new load of tea placed in the brew chamber for a sequental batch of tea to be made. The hot water tank is arranged with a running thermostat system so that the brew water is maintained at an appropriate brewing temperature, usually about 200.degree. F. The reservoir is provided with two openings, one to be disposed below the outlet orifice of the brew chamber, ad a second openign generally adjacent a housing for the siphon system through which a water spout is connected to the dilute line extending from the needle valve assembly to feed the dilute water into the reservoir separate from the tea extract fed from the brew chamber.
In accordance with the invention, the cold water that displaces the hot water for steeping the tea is introduced under pressure generally at the bottom of the hot water container, rather than entering by downward cold wear migration as in typical coffee brewing siphon systems. This causes the water to stratify and form a lower temperature cold water piston effect urging upwardly the much hotter water which had been contained in the hot water container. As a result, the water siphoned from the tank through the siphon tube to the spray head and disc over tea leaves is generally at the desired brewing temperature which the heating element maintains in the hot water tank prior to the initiation of a brew cycle.